Micro-shutters have been used within the prior art as light spatial modulators. One of the more notable of these is U.S. Pat. No. 5,784,189 issued to Bozler et al. and assigned to Massachusetts Institute of Technology (MIT), hereinafter referred to as the Bozler '189 patent. This prior art disclosure taught making spatial light modulators using micro-shutters that were lithographically generated and electrostatically controlled. The individual micro-shutters employed aluminum and required electrostatic control. While useful as teaching a method towards fabricating a light modulation devices with small apertures, the Bozler '189 fails to teach micro-shutter fabrication techniques that are useful under magnetic control.
As shown in U.S. Pat. No. 4,012,828, a Digital Frame Counter is described where the exposures used for a camera are displayed in a digital format. Such a digital frame counter could be a Liquid Crystal Display (LCD). The advantages of this type of display are that individual numbers can be larger than the above discussed rotating wheel, and each frame number can be displayed without resorting to the used of dots as intermediate frame numbers. The disadvantages of this type of display are that LCD's are relatively expensive, require support electronics and can appear dark in low light situations due to their dependence on polarizing filters for them to function.
As seen by the foregoing discussion, it should be readily apparent that there remains a need within the art for a magnetically controlled micro-shutter that is inexpensive to fabricate.